Introduction
According to the theme of Celestial Challenge Structure set by 
As we all know that old people built tunnels to hide in case of wars, this is also kind of same thing, it was built in Byzantine Era (780-1180) and was rediscovered in 1960s.
It's structure was a little different from now a days as the rocks were quite soft that they can hew away but were stronger enough to prevent collapse. It has the capacity to store 20000 people with their food and livetock.
